1. two node cluster setup
2. install the Confluence Gliffy Plugin on one node (called producer node from now on)
3. ensure that the plugin and it's state was successfully synced by visiting /plugins/servlet/upm#manage on the other node (called consumer node from now on)
4. disable the plugin on the producer node
5. ensure that the disabled state got synced on the consumer node
6. re-enable the plugin on the producer node
7. refresh /plugins/servlet/upm#manage again on the consumer node

You will see that the producer node shows "89 of 89 modules enabled" and the consumer node shows "88 of 88 modules enabled" for that plugin.

Also when the plugin is disabled, both nodes will show "0 of 88 modules enabled". The missing module is the "Rest Servlet Filter(gliffy-api-rest-filter)". Note that the missing module is not part of the atlassian-plugin.xml descriptor and seems to be added dynamically by the RestModuleDescriptor.

I've constructed a minimal plugin

<atlassian-plugin key="rest-test" plugins-version="2">
	<rest key="rest-rest" path="/rest/test" version="1.0"/>
</atlassian-plugin>

and put this in a file named atlassian-plugin.xml and compressed it with the zip algorithm into the attached rest-test.jar. But if I install this plugin via UPM into the cluster and disable/enable it, the state gets correctly propagated and the receiving node will still have a Rest Servlet Filter(rest-rest-filter) module.